LinuxCNC not launching

My system is handing on launch. The Axis toolchanger appears briefly - as normal, but the main window doesn't appear. Re-launching doesn't work, the computer has to be rebooted. The rest of the OS works fine, but tit will not re-boot, it has to be powered off at the switch and re-started, as if it is being blocked by a process. 
Running Version 2.8, but have been using this system for around 10 years without a hitch until recently. 
It started off being an occasional random occurance, but now it seems permanent. Very frustrating.

Any suggestions welcome.

Thanks

Dave

pull the cards, sounds like a hardware issue

Failing power supply, memory or memory controller, MB caps, HDD, in that order.
If there are more than one memory module, yank them out and test 1 by 1.
You can also use a USB with any Linux on it to boot the PC, use it for a while, see how it behaves as the Live versions do not use HDD.

Thank you both for the replies. Well, I've had my money's worth from that old PC. At least 15 years old. I bought a newer PC and parallel port card a while back for this situation. Best dig it out, fire it up and check if the parallel port is compatible. Wish me luck!